The present invention relates to a higher order mode generator device capable of converting the 0th order fundamental waveguide mode into the higher order waveguide modes through an external control.
Combining different orders of waveguide modes in a waveguide type device is very difficult and also has a fundamental problem. If solving these problems, it can be applied to various devices such as a switch or an attenuator. As such passive devices capable of combining the fundamental mode into the higher order modes, only passive devices composed of adiabatic Y-branch type waveguides having different widths have been reported. There has been no device that can control the amount of combination using external voltage or current. In case of using the adiabatic Y-branch type waveguide, fabrication of optical devices such as 2xc3x972 switches and optical attenuators is possible by combining two Y-branches in the form of Mach-Zehnder interferometer. In these cases, however, there are difficulties in the fabrication since the branching angle of a Y-branch is very small, and also thie optical loss is large since the length is lengthened very long.
An object of the present invention is to provide a higher order mode generator device for converting the 0th order fundamental waveguide mode into the higher order waveguide modes more than a first order, which has a very simple structure composed of a straight waveguide and an electrode.
Another object of the present invention is to provide a higher order mode generator device which can simplify the structure of an optical device and a driving method thereof.
These and other objects can be accomplished by a higher order mode generator according to the present invention, comprising a linear waveguide including upper and lower cladding layers 2,3 and core layer 1 which support higher order modes higher than the 0th order and a linear heater 4 which is disposed across the waveguide at a tilt angle xcex1 with respect to the waveguide, wherein for combining the 0th order optical guiding mode with the mth order optical guiding mode, a tilt angle xcex1 of the heater and the mth order mode propagation angle xcex8m satisfy the condition of xcex1 greater than xcex8m/2.